【leetcode】257. Binary Tree Paths

problem

257. Binary Tree Paths

 solution１:recursive递归方法。

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    void binaryTreePaths(vector<string>& result, TreeNode* root, string str)//取地址符的用法.
    {
        if(!(root->left) && !(root->right)) 
        {
            result.push_back(str);
            return;
        }
        if(root->left) 
            binaryTreePaths(result,root->left, str+"->"+to_string(root->left->val));//
        if(root->right) 
            binaryTreePaths(result, root->right, str+"->"+to_string(root->right->val));
    }
    vector<string> binaryTreePaths(TreeNode* root) {
        vector<string> result;
        if(!root) return result;//
        binaryTreePaths(result, root, to_string(root->val));
        return result;
        
    }
};

solution2:DFS

solution3:BFS

参考

1. Leetcode_257_Binary Tree Paths;

2. Leetcode_discuss_3method;

完